GST Invoice Template: Format, Rules, and Free Download

A GST invoice is a legal document that every GST-registered business in India must issue when supplying goods or services. It is not just a payment request — it is the foundation of the GST compliance chain. Without a correctly formatted GST invoice, your buyer cannot claim Input Tax Credit (ITC), and your business risks penalties during GST audits. This guide covers the mandatory format, required fields, and practical tips for creating GST-compliant invoices.

What Is a GST Invoice?

A GST invoice is a tax invoice issued under the Goods and Services Tax regime in India. It documents the supply of goods or services, the tax charged, and the parties involved in the transaction. Unlike a simple commercial invoice, a GST invoice has legally mandated fields that must be present for the document to be valid under GST law.

Under Section 31 of the CGST Act 2017, every registered taxable person must issue a GST invoice at the time of supply. The invoice serves three critical functions:

• Tax documentation — proves that GST was charged and collected on the transaction
• ITC enablement — allows the buyer to claim Input Tax Credit on GST paid
• Audit trail — provides evidence for GST return filing and government audit

Mandatory Fields in a GST Invoice

Rule 46 of the CGST Rules specifies the following fields that must appear on every GST invoice:

Supplier Information

• Name of the supplier — legal name as registered with GST
• Address of the supplier — principal place of business
• GSTIN of the supplier — 15-digit GST Identification Number

Invoice Identification

• Invoice number — unique, sequential, maximum 16 characters, containing only alphabets, numerals, hyphens, and slashes. Must not be repeated within a financial year.
• Date of issue — the date the invoice is created

Recipient Information

• Name of the recipient — legal name (required if registered)
• Address of the recipient — billing/delivery address
• GSTIN of the recipient — if registered under GST (for B2B transactions)
• Place of supply — state name and state code (determines whether CGST+SGST or IGST applies)

Item Details

• Description of goods or services — clear, unambiguous description
• HSN code (for goods) or SAC code (for services) — harmonized system code that classifies the product/service for tax purposes
• Quantity and unit — the number of units supplied with the unit of measurement
• Total value before tax — taxable value of the supply
• Discount — if any, shown separately

Tax Details

• Tax rate — the applicable GST rate (5%, 12%, 18%, or 28%)
• Tax amount — broken into CGST and SGST (for intra-state supply) or IGST (for inter-state supply)
• Total invoice value — taxable value plus tax amount

Additional Required Information

• Whether tax is payable on reverse charge basis — if applicable, must be explicitly stated
• Signature or digital signature — of the supplier or authorized representative

Intra-State vs. Inter-State: Which Tax Applies?

The place of supply determines which GST components are charged:

Intra-state supply (supplier and recipient in the same state): CGST + SGST (split equally). Example: If the rate is 18%, charge 9% CGST + 9% SGST.

Inter-state supply (supplier and recipient in different states): IGST (single rate). Example: If the rate is 18%, charge 18% IGST.

Getting this wrong is one of the most common GST invoice errors. Always verify the place of supply before creating the invoice. The place of supply is not always the recipient's registered address — for services, it depends on the nature of the service and where it is performed or received.

HSN and SAC Codes: What to Use

HSN (Harmonized System of Nomenclature) codes classify goods. SAC (Services Accounting Code) codes classify services. Whether you need to include them depends on your turnover:

• Turnover up to ₹1.5 crore — HSN/SAC code is optional
• Turnover ₹1.5 crore to ₹5 crore — 2-digit HSN/SAC code required
• Turnover above ₹5 crore — 4-digit HSN/SAC code required

For common services: IT services (SAC 998314), consulting (SAC 998311), graphic design (SAC 998391), accounting (SAC 998221). You can look up your specific code on the GST portal or CBIC website.

GST Invoice Number Format Rules

Invoice numbers under GST have specific requirements:

• Maximum 16 characters
• Only alphabets, numerals, special characters (hyphen "-" and slash "/")
• Must be unique and sequential within a financial year
• May contain multiple series (e.g., for different branches or product lines)

Common formats that comply: INV/2026-27/001, IB-2627-0001, GST-26-001. Choose a format and use it consistently throughout the financial year.

Example GST Invoice

Here is a sample GST invoice for a web development service (intra-state supply within Maharashtra):

INVOICE
────────────────────────────────────────
Supplier: WebDev Solutions LLP
Address: 45 Tech Park, Andheri East, Mumbai 400069
GSTIN: 27AABCW1234F1Z5

Invoice No: WDS/2627/042          Date: 15-Mar-2026

Bill To: Acme Marketing Pvt Ltd
Address: 12 Business Centre, BKC, Mumbai 400051
GSTIN: 27AAFCA9876B1Z8
Place of Supply: Maharashtra (27)

─────────────────────────────────────────────────────
Description          SAC     Qty    Rate       Amount
─────────────────────────────────────────────────────
Website Development  998314   1    ₹80,000    ₹80,000
UI/UX Design         998391   1    ₹35,000    ₹35,000
─────────────────────────────────────────────────────
                                Subtotal:   ₹1,15,000
                                CGST @9%:     ₹10,350
                                SGST @9%:     ₹10,350
                                ─────────────────────
                                TOTAL:      ₹1,35,700
─────────────────────────────────────────────────────

Payment Terms: Due within 15 days
Bank: HDFC Bank, Account: 123456789, IFSC: HDFC0001234
UPI: webdev@upi

Tax payable on reverse charge: No

Common GST Invoice Mistakes to Avoid

• Wrong place of supply — charging CGST+SGST for inter-state supply (should be IGST) or vice versa. This is the most expensive mistake as it requires credit notes and re-filing.
• Missing GSTIN of the recipient — for B2B transactions, the buyer cannot claim ITC without their GSTIN on your invoice.
• Incorrect HSN/SAC codes — using the wrong classification code can trigger notices and demand for differential tax.
• Non-sequential invoice numbers — gaps in your invoice numbering sequence invite scrutiny during audits.
• Invoice dated before supply — for goods, the invoice must be issued at or before the time of supply. For services, within 30 days of supply.
• Missing reverse charge declaration — if reverse charge applies, it must be explicitly stated on the invoice.

Generating GST Invoices with InvoiceBlitz

InvoiceBlitz's free invoice generator includes all mandatory GST fields pre-configured for Indian businesses:

• GSTIN fields for both supplier and recipient
• Automatic CGST/SGST or IGST calculation based on place of supply
• HSN/SAC code field for each line item
• Sequential invoice numbering that complies with GST format rules
• Place of supply dropdown with state codes
• Professional PDF output with all required tax details

You can create GST-compliant invoices without worrying about missing fields or incorrect tax calculations — the system handles compliance automatically.

FAQ

Is a GST invoice required for all transactions?

A tax invoice is required for all taxable supplies by registered persons. For exempt supplies, a bill of supply is issued instead (without tax details). For supplies under ₹200 to unregistered consumers, a consolidated invoice at the end of the day is acceptable.

Can I issue a GST invoice in a foreign currency?

Yes, for export transactions. However, the tax amount must be shown in Indian Rupees. You can show the invoice value in the agreed foreign currency and the GST component in INR using the exchange rate on the date of supply.

What happens if I make a mistake on a GST invoice?

Issue a credit note (for overcharge) or debit note (for undercharge) referencing the original invoice. GST invoices cannot be modified after issuance — corrections must be made through supplementary documents that reference the original invoice number and date.

How long must I retain GST invoices?

GST law requires retention of all invoices and related documents for at least 6 years (72 months) from the due date of filing the annual return for the relevant year. Digital storage is acceptable and recommended.

Create your invoice online with InvoiceBlitz with full GST compliance built in — no manual formatting required.